When we took on the job of consolidating and conserving Room 34 of the Domus Aurea, the tasks and difficulties to be tackled seemed fairly circumscribed.
The preliminary examination of the wall structures (obviously carried out at ground level) evidenced a vast gap of about 20 square metres in the outer wall whose highly irregular profile indicated urgent problems in the shape of a danger of sudden collapses.
The surviving part of the outer facade showed small traces of a jack arch and a safety arch; the remaining surface was reduced to the wall core. The interior facing, preserved to a greater extent, seemed to be better conserved.
The objective to be achieved was therefore demanding in economic and organizational terms but all things considered not too complex as concerned project choices.
Essentially, the work entailed reconstructing a brick facing, unfortunately of limited thickness (70-75 centimetres), using materials and procedures in line with those of antiquity on a wall forming the external south-facing facade of the Domus.
We therefore needed to build external wall facings in opus testaceum on the outside and, on the inside, another wall facing and opus reticulatum. The preliminary examination suggested that the internal wall core was made in the traditional way with mortar and tufa blocks.
So we began work, erected the scaffolding and were thus able to examine the structural features of the room close up (at a height of 10 metres).
Many predictions and some beliefs had to be revised.
First of all, we were able to see that over time the wall had rotated towards the outside by a distance of about 4-5 centimetres measured at the top, a considerable amount that had created a detachment between the wall itself and the vaulted room which had apparently stabilized.
Furthermore, the examination of some fragments and imprints of bricks at the top of the wall raised questions about the relative timing of the construction of the outer walls and the rooms inside. In other words, what was the actual order of construction of the walls, jack arches, safety arches and windows (and their subsequent blocking up) between the first and second century AD?
We are adapting our intervention to this new information, considering also that the original wall core was made using whole or fragmentary bricks instead of the little tufa blocks generally used in the Domus.
Additionally, the construction of the outer wall facings seemed hurried, using bricks of different thicknesses and types, but roughly respecting the horizontal courses.
Finally, some tests carried out on the imposts of the vault unfortunately indicated the fairly advanced deterioration of the mortars and tufa blocks of which they are made; this is the result of many centuries of percolation affecting the monument (the consistency of the damp tufa blocks now resembles sand); we therefore immediately updated the structural project, which currently entails constructing a counter-vault in small bricks laid on edge and adhering to the original vault, over a significant portion of the room.
The final remark to date concerns the discovery and need to protect numerous decorated surfaces and some stucco elements, invisible before the scaffolding was erected. Their discovery also forces us to reconsider the original function of Room 34 in the architectural and distributional layout of the Domus Aurea.
In brief, our intervention now requires extra funding for works which could not have been foreseen during the planning stage, such as:
- the wall core on the outer facade to be built using small bricks;
- the plaster and stucco elements to be protected;
- the counter-vault and consolidations to be put in place with urgency.
And that may not be all.
Despite its small size, Room 34 is representative of the difficulties faced in the Domus Aurea, whose complexity and multi-faceted nature are the object of continuous studies and updates.